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Do you remember those pretty field lines that emerge when you scatter iron filings around a magnet? In the case of a simple magnet the field is static; it doesn't change with time. But magnetism is just one aspect of something bigger: electromagnetism. You are at this very moment immersed in electromagnetic fields, generated by the Earth, the Sun, and even your toaster.

James Clerk Maxwell realised, in 1864, that electricity and magnetism were just two sides of the same coin and that light was made up of electromagnetic waves. He developed an elegant theory describing the unified force of electromagnetism and the equations that describe the dynamics of an electromagnetic field now carry his name.